table Kv
  key as text
  ival as int
  tval as text
  -- number are stored in ival
  -- date are stored in both
  -- text set ival to null
view getIvar
view getTval

predicate:
  view equal
  view bigger
  view smaller

  --first ival , if null then tval

boolean:
  view and
  view or
  view not
  view xor
  view ok -- fornnested view

nested boolean:
  view andor
  view orand
  ...
  
.